Developmental changes in high-affinity uptake of GABA by cultured neurons

High-affinity uptake of ³H]-aminobutyric acid (GABA) was studied in cultures of neonatal rat cortical neurons grown on pre-formed monolayers of non-neuronal (glial) cells. Both the maximum rate (V _max) and, to a smaller extent, theK _m of ³H]GABA uptake increased with time. In addition, in parallel with these changes, 2,4-diaminobutyric acid and cis-3-aminocyclohexane-1-carboxylic acid (ACHC), compounds which are considered typical substrate/inhibitors of GABA uptake in neurons, became progressively stronger inhibitors of ³H]GABA uptake. Consequently, the present results may mean that the studies using uptake, of ³H]GABA, ³H]ACHC, or ³H]DABA as a specific marker for GABAergic neurons differentiating during the ontogenetic development of the central nervous system may have to be interpreted with caution.